I would not simply submit a refund claim but rather I would submit a refund claim for the difference betwhen what I actually paid and what I could have gotten what I got for, namely the difference between full first and deep discount economy. Admittedly the dollar amount for the OP is small because SFO-LAS is a small fraction of the trip HKG-LAS.

The person who said he was downgraded more than twice intrigues me. This would look like a situation where, if the first refund request was denied, then the second go round would have me asking for the complaint resolution officer. If I had indeed checked in and arrived on time the complaint would be made prior to departure. This should make the FA breath a sigh of relief because it would be the CRO who takes the late instead of the FA.
If I just "almost missed the connection" the issue would be after departure with the GA to book a satisfactory alternate flight.

An airline should be "standing on its head" to accommodate paid first, and pushing a few extra buttons that forcibly book the next operating flight following a missed connection sounds like an excellent and simple solution.